Telegraph switching system



1,642,037 c. E. LOMAX TELEGRAPH SWITCHING SYSTEM Filed Ju1y6, 1925 2 Sheets-Shet 1.

Sept. 13,1927.

Inun or Clarence E Lumax HTZ':

Se t. 3 192 p 1 7 c. a LOMAX TELEGRAPH SWITCHING SYSTEM Inu'sn ur' Clarence E. L nmax Patented Sept. 13, 1927.

UNITED STATES 1,642,037 PATENT OFFICE.

' CLARENCE E. LOIIIAX, CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE.

Application filed July 6,

This invention relates in general to telegraph switching systems, moreparticularly to such a system in which a plurality of telegraph stations of closed circuit type, may be selectively switched together by means of a remote control automatic switch without interrupting the closed telegraph circuit.

Specifically the invention relates an mproved telegraph switching system, in which an automatic switching mechanism can be directively controlled to connect a sending station and a selectable receiving statlon together, the switch also operating to connect a common receiving station in the ser1esc1rcuit comprising the three mentioned stations.

In Patent No. 1,581,844, issued to me on April 20, 1926, I disclose a telegraph switching system in which I connect two closed circuit stations together without opening the circuits of these stations. The present 111- vention is inthe nature of an improvementof my priorcase, in which I modify the c1rcuits as set forth in the annexed specification. v

In order. to more fully explain the object of my invention I will cite an example of an installation made in accordance with the object of my invention. "In large hotels considerable attention must be paid to a paging system which enables the hotel management to quickly locate any guest of the hotel To expedite service of this klnd, have designed a printing telegraph switching system, in which a plurality of receiving printers are controlled from a common sending station to give directions to the hotel pages so that they may quickly locate the wanted guest. In this system I provide a printing telegraph receiver for each floor of the hotel, this receiver being located at the floor clerks Office. In the telephone room,- which, be cause of the nature of its business, is' the logical place for the sending mechanism, I install a plurality of printing telegraph senders. In the completion of this system I install at the bell captains station another printing telegraph receiver, which is operated simultaneously with any floor receiver by the sending station in the telephone room. If, for example, the telephone operator receives a call for a guest registered in a room on the fifteenth floor, and that guest does not respond to his room telephone, she may oper* ate the e uipment of my invention to call the floor cler of the fifteenth floor. By switch- -TELEGRAPH SWITCHING SYSTEM.

1925. Serial No. 41,469.

telegraph, to print and record the name androom number of the desired party, so that the bell captain and floor clerk can dispatchpa es to rapidly locate the wanted party.

7 ccordingly, one of the objects of my in-- vention is to provide a switching system that Wlll connect a selected receiving station and a common receiving station together with and under the control of a sending station.

Inasmuch as the bell captains receiver or the floor receiver may be engaged at the moment that the operator makes the above call, have provided a double. busy test feature, which will operate in case either one or both of the wanted. receiving stations are busy to prevent the switch mechanism from extending a connection to the station, and toreturn a distinctive signal to the sendin station to notify the operator that the cal she is extending is not completed.

To facilitate the paging service, I have as a further object of my invention provided circuit arrangements so that each floor receiver may be called by two different numbers, the [first number connectin that receiver and the calling sender wit one bell captains receiver, and the other number substituting a second bell captains receiver.

A still further object of my invention is to provide a repeater so that a large number of printing telegraph receivers can be operated simultaneously from one sender.

. Further objects of my invention not specifically referred to here will be apparent from the detailed specification and claims which follow.

The drawings comprising Figs. 1 and 2, when arranged with Fig. 1 above Fig. 2 with the correspondingly numbered lines in alignment, show sufficlent details to enable a clear understanding of my invention.

In Fig. 1, I have shown three combined sending and receiving printing telegraph -mechanisms represented by the squares S,

S, and 8. .These mechanisms may be any of the well known printing telegraph mechanisms such as that shown in the Patent No. 1,419,677 issued to C. L. Krum et al., June 13, 1922. The automatic selecting switch C, which is individual to the sender S is controlled by the calling device CD shown in Fig. 2 and has access to three sets of banks B, B and B through which it controls the connection.

This switch is preferably a Strowger vertical and rotary motion switch, such as is shown in the Patent 815,176 issued March 13, 1906, to Keith, Erickson and Erickson, with the circuits modified in accordance with the objects of this invention. As will be readily understood this switch has access to 100 sets of terminals which are arranged in ten horizontal rows of ten terminal sets per row.

At FR, I have shown a diagrammatic representation of one of the floor receivers which is accessible to the switch C throu h the bank B. This receiver may be of t e type shown in the above mentioned Krum patent, or it may be a receiving mechanism only such as is shown in Telegraph and Telephone Age of May 16, 1922, in Fig. 2 on page 226. There are as many floor receivers as there are floors in the building all of which are accessible through the contacts of the bank B.

In Fig. 2, I show the control relay sets CR, CR and CR, which are associated with the sending mechanism S, S, and S respectively, of Fig. 1. These control relays are operated through the bank B by the control switch in a manner which will be explained hereinafter.

Associated with the control relays and senders is a calling device or impulse sender CD through which the selective switch C is controlled. This calling device is preferably the well known calling device of the automatic telephone system, which is explained and illustrated'on pages 39 to 42, inclusive, of the second edition of Automatic Telephony by Smith and Campbell.

At GR in Fig. 2, I have shown the common relays which are connected with the control rela sets for a purpose which will he explains hereinafter. At R, R R and R I have shown receiving stations similar to those explained in connection with the floor receiver FR. These latter receiving stations are bell captain stations and are common to the floor calls by means of the control relay in a manner w iich will be explained in detail hereinafter. At H in Fig. 2, I have shown a repeater by means of which it is possible to operate a eater number of receivers simultaneously om sending mechanism. The construction of the above referred to printing telegraph mechanism is such that it is impossible to operate more than three mechanisms in series, that is, a sending mechanism and two receiving mechanisms, and I- have therefore arranged the repeater H so that I may operate the sending mechanism and four receiving mechanisms simultaneously.

In order to simplify the drawings, I have shown a plurality of batteries, whereas in an installation there would be a battery for controlling the control switch C and the relay group CR. CR CR and GR, with a commerclal llO'volts, direct current source of gower to control the telegraph mechanisms and R.

In extending a call through the system of my invention the operator at the sending and control station operates the key associated with the calling device CD to seize the control switch, and by means of the calling device sets that switch into connective relation with the bank terminal leading to the wanted receiving station, such as the station FR. Through the medium of the bank B the control relay group OR is operated to extend the connection from the sending mechanism S, through the control relay group CR, through the bell captains receiver R to battery. A connection is also extended by means of the switch 0 from the sender S through the wipers of the switch C to the bank B to the floor receiver FR.

Associated with the sender S and the control relay GR is a control switch similar to C, which is not shown in Fig. 1 in order to avoid undue complication of the drawing. This switch is controlled by a calling device CD in a manner identical with that explained in connection with the switch C. Associated with the sender S and control relay CR are relays, similar to those associated with sender S and control relay CR, and a third switch similar to switch 0, which is controlled by the calling device CD. The banks of these three or more switches are multipled in banks B and B, that is, corresponding contacts of the banks of each switch are connected together. The bank B however, is not multipled between the switches, but is connected individual to each switch "for a purpose which will be explained in detail herelnafter.

Having thus described my invention in general, I will now proceed with a detailed description of its operation as calls are set up through it.

Before tracing a detailed circuit of a connection involving a sender and one or more receiving mechanisms, it is well to note that the printing telegraph mechanisms referred to in the above Krum patent are closed cir cuit mechanisms, that is, the operating ma nets of these devices are normally energize and are deenergized to throw them into operative position. For exam le, the floor re.-

ceiver FR, Fig. 1 is contro led by the mo tor start relay 18, which is normally energized through the obvious circuit including springs 95 and the resistance 42. The type magnet 19 of this receiver is closed normally through a circuit from ground through the magnet 19, through springs 96, resistance 43, to battery. Similarly the sending mechanism S is controlled by the motor start magnet 12 whose circuit is normally closed-over the path from ground through the magnet 12, through springs 72 conductor 156,

springs 94, resistance 47 to grounded battery; and the type magnet 13 of the sender the motor start magnet 30, which is normally energized in series with'the type magnet of the receiver over a circuit traceable from ground through the, magnet 30, conductor 179, springsllO, 108, 104, conductor 177 through the winding of the type magnet 29 to battery.

The repeater H is controlled by the start i magnet 32 and the type magnet 31, which are also normally energized in series with each other over a circuit traceable from ground through magnet 32, conductor 181, springs 112, 106, 102, conductor 178, conductor 180, to resistance 44, through .magnet 31 to grounded battery. And lastly the receivers R R and R are controlled by the motor start relays 33, 35, and 37, respectively,

I which are normally energized over theobvious circuit including resistance and spring 125; and are operated by the type magnets 34, 36,- and 38, respectively, which are norrhally energized over the obvious circuit including resistance 46 and springs 124.

In Working out these circuits in accordance with the objectsof this invention, it is necessary to switch'together two or more of these printing telegraph mechanisms with-' out opening the local circuit, particularly the type magnet circuits and allowing the type magnets to restore.

The telephone operator, upon receiving a call which necessitates connectingthe floor receiver FR and the bell captains receiver R together, consults her directory and finds, for example, that that combination is reached by dialling 11. She then operates the key 115, closing a circuit for the line relay 2 of the control switch C, which is traceable from ground through the signal L, through the interrupter springs 116 of the calling device CD, through the key springs 115, over conductor 131, through springs 71,

- through the two windings of relay 2 in series to grounded battery. Relay 2 energizes over the circuit and at spring 73 and its make contact closes the obvious circuit for relay 3. Relay 3 energizes and at spring 74 closes a circuit from ground through spring 74 and its make contact to the release trunk conductor 152, thereby placing busy guarding potential upon the contacts 200 and 201 to prevent the switch C from being seized from this path; Relay 3 upon energizing also interrupts the circuit of the release magnet 48 and'pr-cpares a point in the impulsing circuit. The operator then operates the calling deviceCD to transmit the digit 1, the calling device operating in the well known manner to close the shunt springs 117 thereby affording a direct ground path excluding the signal L, during impulsing. The

impulse springs 116 interrupt the above traced circuit to relay 2, which falls'back and at spring 73 breaks the previously traced circuit to relay 3. However, relay 3 is slow to release because of a copper slug on its core and-remains in energized position during impulsing. Relay 2 upon falling back closes a "circult 'from ground through spring '73 and its break contact, over conductor 163, through springs 93, conductor 164, through spring 75 and its make contact, through ofi normal spring 78 and its break contact, through the Winding of relay 4, through the winding of vertical magnet 10 to grounded battery. Vertical magnet 10 and the relay 4 energize over this circuit, the former following the impulses and the later remaining energized during the impulses because of the copper slug on its core. The vertical magnet upon energizing steps the shaft containing-wipers 50 to 53, inclusive, up one step and operates the off normal springs 76. and .78 in the well known manner. Ofi normal spring 78* changes the above circuit of the 4 vertical magnet, directing itthroug'h spring 78 andits make contact, through sprin 77 and its make contact, relay 4 having energized on the first impulse,'and. then over, the previously described circuit to the relay 4 and the vertical magnet 10, so that addieen tional impulses',-if there are any, will traverse a path including the spring 77 and its make'contact. At the end of transmitting the first digit, in this case comprising one impulse, relay 2 comes to rest energized, breaking the circuit of relay 4, which falls back after an interval and prepares the circuitfor operating the rotary magnet 11 on the second digit. 'erates the calling device CD to transmit the second digit of the call number, in this case 1, interrupting the circuit of line relay 2 as before. Line relay 2 falls back and closes a circuit from ground to spring 73 and its break contact, conductor 163, springs 93, conductor" 164, through spring 75 and its make contact, through spring 78 and its make contact, spring 77 and its break contact, conductor 165, springs 86, conductor 166, through the winding of relay 5 and the The operator thenreoprotary magnet 11 to grounded battery. The

bank contact. Relay 5 energizes upon the first impulse and remains energized through out the impulsing because of the copper slug on its core. Relay 5 upon energizing closes at spring a link in the circuit of relay 5,

which is in parallel with the springs 86. Relay 5 upon energizing closes atspring 79 a circuit for the relay 7, which energizes and at springs 82 and 83 prepares a testing circuit which will be explained later.

Upon the completion of the transmission of the second digit, the wipers 50 to 53, inclusive, are resting in. contact with the desired bank terminal, in this case assumed to be the bank terminals 55, 56, 58, and 60. Relay 2 comes to rest energized at the end of the impulsing and at spring 73 opens the circuit of relay 5, which restores after an interval, opening the circuit of relay 7, which also restores after an interval.

The operation of the switch D at this point depends upon whether or not the mechanism reached through the four mentioned contacts is busy or idle at the moment. Assuming first that it is busy, the bank contacts 55 01 56 of the bank B will contain the bus ground potential. Assuming first that the bank contacts 55 is grounded, the condition resulting when the bell captains receiver R is engaged. The wiper 50 will then pick up the round from the contact 55, closing a circuit from that ground through the wi )er 50, through springs 88, conductor 1 1, through the winding of relay 6 to battery. Relay 6 energizes and at sprin 81 and its make contact closes a circuit rom ground through resistance 40, through springs 81, through springs 82 and 83, relay 7 not yet having had time to fall back, -conductor 168, through springs 91, through the winding of relay 8, to grounded battery. Relay 8 energizes over the above circuit and at springs 86 interrupts the previously described circuit to the rotary magnet, thereby preventing further rotation of the switch C, should the operator inadvertently reoperate the calling device. Relay 8 at spring prepares a locking circuit for itself, which is completed when the relay 7 1'estores. the circuit being traceable from grounded release trunk conductor 152, through spring 85 and its make contact, spring 83 and its break contact, conductor 168, springs 91, through the winding of relay 8, to grounded battery. Relay 8, at spring 87, also closes a-shunt path for the upper winding of the line relay 2, which is traceable from the upper terminal of the upper winding of relay 2 to conductor 161, through springs 84, springs 87, conductor 162,'to the junction of the upper and lower windings of relay 2. This shunt short circuits the high resistance upper winding of the relay 2, leaving only the low resistance lower winding in series with the signal L at the calling device CD. The resist means"? ed, a condition which will ensue when the floor receiver FR is engaged. Wiper 51 will engage this grounded contact and will close a clrcuit from this ground through wiger51, conductor 167, springs 82 and 83 an thence over the previously described circuit through the relay 8. The relay 8 energizes, and prepares its own locking circuit which is completed when the relay 7 restores as before. Relay 8 operates the previously described circuit to bring up the signal L to again notify the operator that the combination called is inaccessible.

When the relay 6 energizes it also closes a circuit from ground through the resistance 40, through spring 81, through the conductor 167, through wiper 51 now in engagement with bank contact 56, throughconductor 160, through the-winding of relay 20, to grounded y battery. Relay 20 being marginal does not energize in series with the resistance 40, so that this circuit is closed without effect at this time.

Assuming now that neither the floor receiver FR nor the bell captains receiver R,

are engaged at the time the operator makes the above described call, there will be no ground present on either contacts 55 or 56. Consequently relays 6 or 8 will not be energized. When relay 7 restores, it closes a circuit traceable from ground to spring 85 and its break contact, conductor 169, through the upper winding of relay 9, through conductor 170, through spring 82 and its break contact, through conductor 167, through wiper 51, now in engagement with bank contact 56, through conductor 160, through thewinding of relay 20 to grounded battery. Relay 9 energizes over this circuit and atspring 89 and its make contact closes a locking circuit for itself, traceable from grounded release trunk conductor 152, through springs 89. over conductor 172 and-the lower winding of relay 9, to grounded battery. Relay 9, upon energizing closes springs 90, thereby closing a circuit from ground through these springs, through wiper 51 and thence over the previously described circuit through relay 20, which now energizes, and at spring 95 opens the normally closed circuit of motor start relay 18, allowing that relay to restore and to start the motor of the receiving mechanism FR. Relay 2O removes battery from the normally closed local circuit of type magnet 19, preparing that magnet for the reception of impulseswhich will be delivered from-the sending mechanism. Returning now to the control switch, relay 9 upon energizing also breaks the circuit from relay 6 to the wiper 50 at spring 88; breaks the circuit of the relay 8 at spring 91; breaks the previously described impulsing circuit at springs 93, and

bank contact 58, over conductor 139, through i the winding of relay 22, over conductor 175,

through the winding of relay 27 to grounded battery. Relays 22 and 27 energizes over this circuit, the former preparing a circuit for the type magnet 29 of the bell captains receiver R, and the latter placing a ground on the conductor 150, which is multipled through the bank B, to protect the connection from intrusion. Finally relay 9 at springs 94,

opens the normally closed circuit for the type magnet 13 of the sending mechanism S and closes a series circuit traceable from ground through relay 19 of the floor receiver" through .contact of the bank B wiper 53, spring 94 and its make contact, conductor 153, through the interrupting springs 97 of the sending mechanism S, type magnet 13 of the sending mechanism, conductor 132, through spring 101 and its break contact, spring 103 and its make contact, conductor 177 through the winding of type magnet 29 of the-bell captains receiver R, to grounded battery. The operator then operates the sending keyboard of the sending station S, causing the interrupter springs 97 to interrupt the previously traced circuits for type magnets 19, 13, and 29, to transmit the esired paging orders simultaneously to the bell captain and the floor clerk. I

-When the operator has completed the sending of the paging orders, she restores the key, .115, thereby opening the previously traced circuit tothe line relay 2 of the control switch C. The line relay restores and at spring 73 opens the circuit of the release relay 3, which restores after a brief interval and removes the holding ground from the release trunk conductor 152. Relay 9, which was locked to the release trunk conductor through springs 89 and the lower winding of the relay, then restores, and at spring 94 and its break contact closes the holding circuit for the type magnet 13 of the sender and for the type magnet 29 of the bell captains-rec'eiver R. Relay 9 upon restoring also opens the previously described circuit for relay 20, allowing that relay to restore and again close the local holding circuits in the floor recciver'FR. Relay 9 upon restoring also closes the release circuit of the switch which is traceable from ground, through spring 73 and its break contact, conductor 163, springs 93, conductor 164, sprin 75 and its break contact, through ofi normal spring 76, through the winding of release magnet 48 to grounded battery. The release -magnet energizes over the above traced circuit and operates to restore the shaft, containing wipers 50 to 53, inclusive, to normal in the well known manner. When the shaft reaches a normal position the oil normal springs 76 and 78 are voperated,spr ing 76 breaking the circuit of the release magnet thereby restoring the control switch C to normal. Relay 9 at spring 92 opens the previously described circuit for the relay 22 of the control relay group CR and the relay 27 of the common relay group GR, allowing those relays to restore, the former to se arate the local circuit of the sending station S from the local circuit of bell captains receiver R, and the latter to remove the protecting ground from the bank terminal 55 of the bank B.

If while the operator was setting up the,

above mentioned connection she had received a busy signal due to the busy condition of the bell capt-ains receiver R, she could have released the connection immediately by operating the key 115 to normal and set up a new connection by dialling the digits 21, which would connect the floor receiver FR with the repeater H and the receivin mechanisms R R R". Operation oft e calling device transmitting the digits 21 operates the control switch in the above referred manner and, at .the completion of the transmitting of the impulses, the wipers 50 to 53, in-- elusive, are in contact with bank contacts 53', 54, 57, and59, respectivel Assuming that both the floor receiver F and the repeater H are idle at the moment, there will be no ground present in the bank contacts .534 and 54 and the relay 9 will energize as before closing the followi circuits: relay 9 at spring 90, closes a circuit through wiper 51, now in engagement with contact 54 over conductor 160 to relay 2Q, ener 'zingthis relay, as hereinbefore set forth. elay 9 at spring 92 closes a circuit from ground through spring gagement wit bank contact 57 and with conductor'140, through the winding of relay 21, over conductor 176, through the winding,

of relay 28, to grounded negative battery. Relays 21 and 28 ener ize, the former to break the local circuit 0 the sending mechanism magnet 13 and to associate that mechanism with the repeating mechanism H, and the latter to connect guarding-ground to conductor 151 to protect the call from intrusion. Relay .9, at spring 94- closes a series circuit for the type magnets 19, 13, and 31 over a circuit traceable from ground to relay 19, over conductor 159, to bank contact 59, wiper 53, spring 94 and its make contact, to conductor 153, through interrupting sprin 97 of the sending mechanism S, through type magnet 13, conductor 132, through 92 and wiper 52 now in ensprings 101 and the make contact, conductor 178, conductor 180, through resistance 44, type magnet 31 of the repeater H to grounded battery. The operation of relay 21, at sprin 102 opens the normal circuit of relay 32, W ich was held energized in series withrelay 31 over the previously traced circuit. Relay 32 deenergizes and opens the circuits of motor start relays 33, 35, and 37 of the receivers R R and Rfi'respectivel The operator then operates the keyboar of the sending mechanism S to cause the interrupter springs 97 to interrupt the previously traced circuit of the type magnets 19, 13, and 31, respectively, magnets Band 31 operating to register the message on the tape of the floor receiver FR and sending mechanism S, respectively. Type magnet 31 of the repeater H at springs 124 opens and closes the circuit oi type magnets 34, 36, and 38 of the receivers R R and R respectively, repeating the message to these receivers, which are operated under the control of their re spective type magnets to record the message on the tape.

The operator upon completing the message restores the key 115 to normal, releasing all equipment in the manner hereinbefore described.

It is understood that I have shown the second bell captains receiver replaced by the repeater H which repeats into the receiving stations R R and R merely for the purpose of illustrating the action of the repeater H. A receiving mechanism such as R could replace the repeater H, the conductor 180 corresponding to the conductor 177 of the receiver R and the conductor 181 corresponding to the conductor 179. An installation utilizing a repeater in the second choice bell captains circuit would be rare although it might have the utility in a hotel which had several branches and which maintained bell captain stations in the main hotel and in each branch, to page a guest who might be in any one of the various branches of the institution.

In a similar manner the operator may use the sending mechanism S and its associated control switch, not shown, by manipulation of the calling device CD, in which case the relays 23 and 24 operate to connect the repeating station H with the sending mechanism and the selected floor receiver, or the relay 24 operates to connect the bell captains receiver R'with the sending mechanism S and the selected floor receiver FR; Furthermore the sending mechanism S is controlled by the calling device CD and the associated control switch, which is not shown, to operate the relays 25 and 26, the tower to connect the bell captains receiver R with the sending mechanism, and the latter to connect the repeater station H with the sending mechanism. The operation of these two additional sending mechanisms and control is identical with that which has been explained and need not be repeated,

I have provided the contacts 200, 201, and 202 associated with the control switch and the sending station S, so that the sending station S may be called from a telegraph switching system such as is shown in my copending application mentioned above. In a hotel telegraph system, such as I have described here, in which the subject matter of the instant application is in the form of a paging system, there would probably be installed in the hotel a separate set of teleraph instruments with associated switch- 1ng equipment substantially as set forth in the above ap lication. This latter system would be used to transmit orders between various departments of the hotel, such as from the floor clerks to housekeeper or to the cashiers oflice, etc. It may be desirable in some instances to connect the house teleraph system with the pagingsystem, for t e purpose of communicating between stations that otherwise would not have trafiic with one another. The bank contacts 200 to 202, inclusive, correspond respectively to the bank contacts 38 to 40, inclusive, of my above mentioned copending application, and are accessible to the switching mechanism H to connect the sendin station such as A to the receiving station a. The station S is in this case a receiving station as well as a sending station, and messages can be sent back and forth over the connection thus established. When the switch H seizes the bank contacts 200 to 201 inclusive, ground is placed upon the bank contact 201 as set forth in the above specification. This completes a circuit over the release trunk conductor152 through spring 74 and its break contact, through the winding of relay 1 to battery energizing the relay 1. Relay 1 at spring 72 opens the normally closed circuit of the motor control magnet 12 of the station S, allowing that magnet to restore to put the station in operating order. The relay 1 at spring 72, removes battery from the type magnet 13 of the station S, the magnet being held energized ,over a series circuit including the conductor 2 and wiper 37 of my above mentioned copending application, that wiper now being in contact with the bank terminal 202, the circuit including conductor 130, spring 103 and its break contact, spring 101 and its break contact, conductor 132, magnet 13, impulse springs 97, conductor 153, spring 94 and its break con tact, resistance 41 to ground. The relay 1, at spring 71, further operates to open the control circuit of the line relay 2 of the control switch C, so that in the event the opera-" tor at station S closes the key 115, the con trol switch will not be seized.

When the messages have been transmitted and received the control switch H is released in the well known manner, ground'being removedfrom the bank terminal 201, allowing the relay 1 to restore and place the receiver S again under the control of its local circuit. I

\Vhile I have chosen to show my invention in connection with a paging'system for use in hotels, I have done so. merely by way of example as there are many other adaptations to which the invention can be readily applied without departing from its scope. Although I have chosen to show my invention utilizing a particular kind of equipment throughout, I do not wish to be limited by the specific disclosure, as there are many modifications and improvements which can be made by one skilled in the art without departing from the scope of the invention. Y

WhatI consider new and desire to have protected byLetters Patentis pointed out in the appended claims.

What is claimed is:

1. .In a telegraph system, a plurality of receiving stations divided into two groups,

a closed local circuit for each station,. a sending station, means for'establishing a connection including said'sending station and a receiving station of each group, said connection being completely established before said closed circuit is opened. 7

2. In a telegraph system, a plurality of Sending stations, a control switch individual ,to each of said stations, a groupof receiving stations accessible from any one of said switches, a group of control relays individual to each switch, other receivers accessible through said relays, means for operating one of said control switches to connect one of said receiving stations to one of said sending stations and means in said switch for operating saidrelays to bring a selected one of said other receivers into said connection. e p

3.' In a telegraphswitching system, a plurality of sending stations having normallyclosed circuits, a plurality of selectable re ceiving stations liavingnormally closed cir-.. cuits, a plurality of common receivmg sta-- tions having normally closed circuits, means ior automatically-Se ecting one of said selcctablc and one of said common receiving stations and means for automatically con-.-

meeting said selected stations to the sending station.

14. In a telegraph system, a sending station, a control switch, a plurality, of receiving stations accessible .from said control switch, a plurality ofcontrol. relay sets, a plurality of receiving stations accessibleto said relays, a-repeater, means dependent up on the setting of said control switch for simultaneously connecting selected ones of I said receiving stations to said sending staand a control magnet, a remote control a-utomatic switch containing wipers, a relay group, means for operatlng said switch to connect a selected one of the receivers of one group to said sending station through said switch banksand ,for connecting a selected one of said receivers in the other group to said sending station through said relay group, means for connecting the type magnets of said three stations together in series'without deenergizing them, and for deenergizing the control magnets of said stations.

6. In a telegraph system, a sending station containing a type magnet and a control magnet, local circuits for maintaining said magnets energized, two groups of receiving stations, each station containing a type magnet and a control magnet, a remote controlautomatic switch containing wipers, a relay group, means for operating said switch to connect a selected one of thereceivers of one group to said sending station through said switch banks and for connecting a selected one of said receivers in the other group to said sending station through said relay group, means for connecting the type series'without deenergizing them and for deenergizing the control magnets of said stations, means for releasing said connection,

means for reenergizing said control magnets and means for reestablishing said local circuits without deenergizing said type magnets.

7. In a telegraph switching system, a send inc station, acontrol switch associated with said station and operable therefrom, a plurality. of receiving stations selectably accessible from the banks of said control switch, another roup of receiving stations, a relay group through which said last receiving stations are associated with said sending station, and means. responsive to a particular setting of said control switch for connecting a selected one of said receiving stations of'the first group, a selected one of saidwreceiving stations of 'the'second group and said sending station operative relation;

8. In a telegraph switching system, a sending station, a control switchassociated with said station and operable therefrom, a plurality of receiving stations selectably actogether in series magnets of said three stations togetherin cessible from the banks of said control switch, another group of receiving stations, a relay group through which said last re ceiving stations are associated with said sending station, means for connecting a selected one of said first receiving stations to said sending station through said control switch and means for connecting a selected one of said second receiving stations to said first through said relay group by a connection excluding said control switch, said means connecting said three stations in series.

9. In a telegraph switching system, a sending station, a. control switch associated with and individual to said station, wipers on said switch, a plurality of terminal groups accessible to said wipers, a plurality of telegraph receivers connected to a certain of said terminal groups, control relays, circuits for said relays established through other of said terminal groups, a plurality of telegraph receivers connected to said control relays, a calling device, means responsive to manipulations of said calling device for setting said switch wipers on selected ones of said terminals, means for operating certain of said control relays to connect one of said second receivers with said sender and means for then connecting the selected one of said first receivers to said sender through said switch wipers.

10. In a telegraph switching system, a sending. station containing magnets, a local circuit for maintaining said magnets normally energized, a control switch containing wipers, receiving stations selectively accessible through said switch wipers, said receiving stations containing magnets and local circuits for maintaining them energized, control relays, a group of receiver stations arranged to be commoned with said sending stationthrough said relays, said receivers containing magnets and local circuits for keeping them normally energized, means for operating said switch to select one of said receiving stations, means then operative to connect the magnets of said receiving station, sending station and one of said common receiver stations together in series, and means for energizing said magnets in series, said first means operatin to substitute said second means for the loca energizing circuit without deenergizing any of, said magnets.

11. In a telegraph switching system, a plurality of groups of telegraph stations, each group comprising a sending stat-ion and'two or more receiving stations, each station having a closed local telegraph circuit, an automatic switch for connecting a sending station and a plurality of receiving stations in circuit, and relay means for establishing a series circuit between said connected stations before opening their local circuits.

12. In a telegraph switching system, a

Leases? sending station, an automatic switch individual to said sending station, a plurality of groups'of receiving stations accessible to said switch, each group comprising two or more receiving stations, said sending station and each of said receiving stations having a closed local telegraph circuit, means at said sending station to operate said switch to connect with a certain group, and means for series circuit between said connected stations before opening their local circuits.

1%. In a telegraph switching system, a sending station provided with a plurality of closed local telegraph circuits, automatic switches, closed local circuit receiving Sta tions accessible to said switches, means at said sending station for operating said switches to connect said sending station in circuit with a plurality of receiving stations, and relay means for establishing a series cir cuit between said connected stations before opening their local circuits.

15. In a signalling system, a sending station, a plurality of receiving stations, a repeater, said 'stationsand said repeater having closed local circuits, an automaticswitch means at said sending station to operate said switch to connect with certain of said reeeiving stations, means controlled by said switch for simultaneously connecting said repeater in circuit with said sending station, and means for establishing a series circuit between said sending station, said receiving station and said repeater, before opening their local circuits.

16. In a signalling system, a sending station, a plurality of receiving stations, a repeater, said stations and said repeater having closed local circuits, an automatic switch, means at said sending station to operate said switch to establish a series circuit between said sending station, said receiving station and said repeater before opening their local circuits.

17. Ina telegraph switching system, a ClOiQd local circuit sending station, an automatic switch, closed local circuit receiving stations accessible to said switch, a closed local circuit repeater, receiving stations accessible to said repeater, and means at said sending station for operating said switch to Ill establish a series circuit between said sending station, certain of said receiving stations and said repeater, said series circuit being completed before said local circuits are opened.

18. In a telegraph switching system, a sending station, an automatic switch, re ceiving stations directly accessible to said switch, arepeater, other receiving stations accessible to said repeater, and means at said sending station to operate said switch in a certain manner to connect a plurality of said directly accessible receiving stations in circuit with said sending station and to operate said switch in a difierent manner to connect certain of said directly accessible receiving stations and said repeater in circuit with said sending station.

19. In a telegraph switching system, a

closed local circuit sending station, an auto-.

matic switch, closed local circuit receiving stations directly accessible to said switch, a closed local circuit telegraph repeater, other receiving stations accessible to said repeater, and means at said sendin station for operating said switch in a certam manner to sible stations in a series circuit with said.

sending stations and for operating said switch in a difi'erent manner to connect certain of said directly accessible stations and said repeater in a series circuit wit-h said sending station.

20. In a telegraph .switchin system, a closed local circuit sending statlon, an automa-t-ic switch, closed local circuit receiving stations directly accessible to said switch, a closed local circuit telegraph repeater, other receiving stations accessible to said repeater, and means at said sending station for operating said switch in a certain manner to con-- nect a plurality of said directly accessible stations in a series circuit with said sending station and. for operating said switch in a different manner to connect certain of said directly accessible stations and said repeater in a series circuit with said sending station, said series circuits being established before said local circuits-are opened.

In witness whereof, I hereunto subscribe 'my name this th day of June, A. D., 1925. 

